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Dan, Technician
Category: Agriculture and Farm Equipment
Satisfied Customers: 5141
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment, trucks and farm equipment - 1995 WyoTech graduate.
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I have a JD 4520 cab tractor. I was using it as normal today,

Customer Question

I have a JD 4520 cab tractor. I was using it as normal today, when I went to get back in it, it showed the PTO was on and gave me an error code 81. The PTO is not on and it will not start. I have looked at the PTO connection on the seat and it is fine. I have tried to engage and disengage the PTO and nothing works. Help! It is three years old.
Submitted: 2 years ago.
Category: Agriculture and Farm Equipment
Expert:  Dan replied 2 years ago.
Hi my name is***** will be glad to try to help. Err_81 is abnormal engine speed update or missing engine speed data. Check the engine speed sensor signal for a faulty sensor or harness problem in the speed sensor circuit. Inspect the harness connector pins and wires for corrosion and damage. Let me know
Customer: replied 2 years ago.
Where is that sensor located?
Expert:  Dan replied 2 years ago.
The sensor will either be in the flywheel housing or on the front timing cover. It will be reading either the flywheel or the front timing gears for engine speed signal.
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